Volume 118, Number 5, June 2017
|Number of page(s)||7|
|Section||Interdisciplinary Physics and Related Areas of Science and Technology|
|Published online||07 August 2017|
Differential adsorption of a membrane skeletal protein, spectrin, in phospholipid membranes
1 Saha Institute of Nuclear Physics - 1/AF, Bidhannagar, Kolkata 700064, India
2 Department of Physics, School of Natural Sciences, Shiv Nadar University Tehsil Dadri, G. B. Nagar, U. P. 201314, India
3 Amity Center for Spintronic Material, Amity University - Sector 125, Noida, U. P. 201313, India
4 Northern Illinois University - 1425 W. Lincoln Hwy, DeKalb, IL 60115, USA
5 Department of Physics, University of California - 9500 Gilman Dr., La Jolla, CA 92093, USA
Received: 8 June 2017
Accepted: 10 July 2017
The interaction of phospholipids with the peripheral membrane proteins like spectrin is important not only to understand the various physiological functions of cells, but also to gain insight into the mechanism involved in the self-assembly of polymer-like long chain molecules at the soft surfaces and interfaces. The lipid head-group specificity of adsorption of spectrin to supported phopsholipid bilayer model membranes has been investigated using the X-ray reflectivity (XRR) technique. Model lipid bilayers composed of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) head groups have been prepared on a soft polymer cushion and the XRR measurements have been carried out from the bilayers immersed in a water bath using high-energy synchrotron X-rays. Our results suggest that in PC-based membranes the spectrin chains form a uniform layer on top of the bilayer with their chains lying on the membrane surface, while in PE-based membranes with relatively smaller head groups, the spectrin chains are attached only through a few possible binding sites with the rest of the part projected out of the membrane surface. In addition, the reflectivity profiles reveal the penetration of spectrin polypeptide chains through the PE bilayer in its fluid phase. Pressure-area isotherm measurements on Langmuir monolayers also support similar observations on the adsorption of spectrin molecules to the membranes composed of PC and PE. The observed results were explained using a qualitative model based on the ion-mediated protein interaction in the PC-based membrane.
PACS: 83.85.Hf – X-ray and neutron scattering / 68.18.-g – Langmuir-Blodgett films on liquids / 87.15.kt – Protein-membrane interactions
© EPLA, 2017
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